The invention relates to an adjustable intake pipe, particularly for supplying combustion air to an internal combustion engine. Adjustment is ensured by a control element, which simultaneously forms the collector chamber of the intake pipe.
Such adjustable intake pipes are known, for instance, from published German patent application no. DE 36 08 310. In this device, the intake air is guided into a control element in the form of a hollow cylinder, which serves as a collector chamber. The outer wall of the control element together with the inner walls of the intake pipe housing forms the annular intake ducts leading to the cylinders. By rotating the control element, the angular position of the opening between the collector chamber and the intake ducts can be adjusted. This permits a continuous (i.e., stepless) adjustment of the intake duct length, so that the vibration conditions within the intake pipe can be optimally adapted to the load condition of the internal combustion engine.
If the intake ducts to the cylinders are arranged in the form of a ring around the collector chamber, the circumference of the collector chamber and thus also its volume are determined by the required length of the intake ducts. This mechanical interrelationship holds true irrespective of whether the cylindrical shell of said collector chamber is used as a control element. The volume created, however, is not required on this order of magnitude. This is a disadvantage since space is unnecessarily wasted even though engine space in motor vehicles is tight.
It is known in the art to use the cylindrical collector chamber for installing other components of the air conduction system. GB 10 12 425, for instance, proposes to install a round filter cartridge, which is supported against the end faces of the intake pipe housing to form a seal. Installing a round filter cartridge as described above, however, means eliminating the adjustability of the intake pipe. This is due to the problem that the round filter cartridge must communicate with the locally fixed air inlet of the intake pipe. In many cases, however, adjustability of the intake pipe cannot be dispensed with, due to the requirement for engine output or efficiency of the associated internal combustion engine.
Thus, despite the efforts of the prior art, there has remained a need for a space-efficient, adjustable intake pipe arrangement.
It is thus an object of the invention to provide a intake pipe which makes it possible to adjust the intake duct length by means of a movable collector chamber shell and, at the same time, optimally uses the clearance required by the unit.
This and other objects are advantageously achieved by providing an adjustable intake pipe comprising a housing having an inlet which opens into a collector chamber defining a volume, the collector chamber having at least one intake duct branching off therefrom; the housing further having at least one outlet per intake duct, wherein the collector chamber is formed by a movably supported control element, and wherein at least one other component of an intake tract formed by the intake pipe is accommodated within the volume of the collector chamber; the at least one component comprising at least one resonance volume, the resonance volume being formed within the collector chamber by at least one partition which has at least one opening and which forms a closed volume.
The intake pipe according to the invention has a collector chamber into which the inlet for the combustion air opens. The collector chamber is formed by a control element having passages to the annular intake ducts. Rotating the control element causes the length of the intake duct to be adjusted. The intake ducts lead to the cylinder-side outlets where the combustion air is introduced into the cylinder head of the internal combustion engine.
In view of the air conduction requirements, the cross section of the collector chamber is overdimensioned. This volume is therefore used to install other functional components of the intake tract. Advantageously, the components can be fixedly connected to either the control element or the housing. To ensure support in the respectively other component, a flexible bearing must be provided. This is necessary particularly in components with relatively large dimensions, since they are located in a pulsating airflow in the collector chamber and are thus subject to vibration stress. The functional components may also be movably mounted in the intake pipe or in the control element.
This makes use of a volume, which must in any event be provided for the intake pipe. This saves space, which functional components would take up in the engine compartment if they could not be accommodated in the intake pipe. In addition, a higher integration density of the components of the engine unit is obtained. As a result, the complexity of the final assembly is reduced. The compact design also reduces the weight.
One advantageous embodiment of the invention provides for an air filter cartridge as the functional component. On the unfiltered air side the air filter cartridge communicates with the inlet of the intake pipe. After the intake air has passed through the filter medium, it reaches the actual collector chamber of the intake pipe. It is advantageous to provide a fixed connection between the intake end of the intake pipe for the unfiltered combustion air and the raw (i.e., unfiltered) air inlet of the preferably cylindrical filter cartridge. A rotatable support may be effected on the end face of the control element opposite the air intake. In principle, however, a fixed support of the filter cartridge in the control element is also possible, in which case a flexible connection is required between the filter cartridge and the air inlet.
According to a further embodiment of the inventive concept, the component may comprise one or more resonance volumes, which communicate with the intake pipe volume by means of an opening. The resonance volumes act as dampers for undesirable air oscillations which build up in the intake pipe. To that extent this measure can improve the acoustic behavior of the intake pipe.
It is advantageous to use parts of the control element wall for the resonance volumes. A fixed connection between the resonance volumes and the control element is therefore suggested. Through a corresponding support in the intake pipe housing, the openings connecting the resonance volumes and the intake pipe volume can be closed and opened. Here, the relative motion between control element and intake pipe housing required by the position of the intake duct length can be utilized. The resonance volumes required for damping the undesirable vibration conditions in the intake pipe can then be added as a function of the operating state of the engine. For a partial addition it is also feasible to incrementally open one or more openings to the resonance volumes. Accommodating additional functional components in the collector chamber of the intake pipe permits better utilization of the engine space.
These and other features of preferred further developments of the invention are set forth in the claims as well as in the description and the drawings. The individual features may be implemented either alone or in combination in embodiments of the invention and/or in other fields of application and may represent advantageous embodiments that are protectable per se, for which protection is hereby claimed.